hot dimmer

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DaveBowden

Senior Member
Location
St Petersburg FL
Have a call to go to tomorrow where the customer says the Leviton single pole slide dimmer in her kitchen is getting hot after the lights haev been on all day. We just installed this a couple of months ago. It is in a 2 gang box with another dimmer. The one getting hot is rated for 600W (500W when installed in a box with 2 dimmers). It has 6 five inch recessed cans with 50W R20 flood lamps in each can for a total of 300W total load.
I don't really want to have to go to a 1000W dimmer if I can avoid it.
Any suggestions as far as things to suspect for the cause?
No the connections aren't loose.
 
kwired

kwired

Electron manager
Location
NE Nebraska
DaveBowden said:
Have a call to go to tomorrow where the customer says the Leviton single pole slide dimmer in her kitchen is getting hot after the lights haev been on all day. We just installed this a couple of months ago. It is in a 2 gang box with another dimmer. The one getting hot is rated for 600W (500W when installed in a box with 2 dimmers). It has 6 five inch recessed cans with 50W R20 flood lamps in each can for a total of 300W total load.
I don't really want to have to go to a 1000W dimmer if I can avoid it.
Any suggestions as far as things to suspect for the cause?
No the connections aren't loose.
Click to expand...

Sounds normal to me. They can and will get fairly hot. Maybe install a stainless wall plate for a little more heat dissipation.
 
Dennis Alwon

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
I agree that it is normal. The dimmers have to dissipate the heat- that's what the fins do so naturally it will get hot near the plate.
 
Besoeker

Besoeker

Senior Member
Location
UK
DaveBowden said:
Have a call to go to tomorrow where the customer says the Leviton single pole slide dimmer in her kitchen is getting hot after the lights haev been on all day.
Click to expand...
As others have said, dimmers get warm. There are a few different circuit arrangements but all (that I've seen) use semiconductors and you might expect 2V or more drop across them. The result is heat.
 
goldstar

goldstar

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I apologize if I'm getting too basic here but if you have 2 dimmers installed next to each other you have to de-rate them. Did you snap off the tabs on one side of each of the heat syncs on the dimmers ? If so, you have to de-rate the dimmers by 150 watts each (for each side you break off). So now each of your 600 watt dimmers is rated at 450 watts. The dimmers will get hot but that's what the heat sync is for - to help dissipate the heat.
 
S

sameguy

Senior Member
Location
New York
Occupation
Master Elec./JW retired
This reminds me of the debate we had about dimmers in a metal or plastic box not long ago. Try search it was long.
 
kwired

kwired

Electron manager
Location
NE Nebraska
goldstar said:
I apologize if I'm getting too basic here but if you have 2 dimmers installed next to each other you have to de-rate them. Did you snap off the tabs on one side of each of the heat syncs on the dimmers ? If so, you have to de-rate the dimmers by 150 watts each (for each side you break off). So now each of your 600 watt dimmers is rated at 450 watts. The dimmers will get hot but that's what the heat sync is for - to help dissipate the heat.
Click to expand...

If you have to snap off the tabs on the sides you have less heat sink, part of the reason for deration. Ambient temperature from other dimmers in same box is another. If you are using the derated dimmer at 450 watts it may get about as hot as a single dimmerconnected to 600 watts.

Bottom line is heat is a normal byproduct of the operation of a dimmer.
 
D

dexterg

Member
Location
New Braunfels, TX
Normal for them to be warm. They must have them dimmed way down, maybe try a 20w lamp if that would be enoungh light or even dimmable CFLS or LEDs. Just my thoughts....
:eek:hmy:
 
S

Strife

Senior Member
What a lot of people don't understand is that when something is rated 90degree celsius, it means it'll get 90 degree celsius when running at the full load specified. The load limitations are because the heat generated by said load and not because of some magic number the manufacturers and engineers come up with. Therefore they build the switch to be able to heat up to 60 degree celsius (or whatever the rating is) and by doing that it can run a 500W load. Have you noticed that the 1000W dimmers are same as the 500W, but they have a heat sink that cools off the switch even when running a higher load? Therefore keeping the temperature at what the dimmer can take and still operate.
A transformer at 90 degree rise will be much bigger than same KVA transformer at 140 degree rise because the 90 degree has to be build to not heat more than that when at full load. So basically the manufacturer takes a 150KVA at 140 degree and make it 112.5KVA at 90 degree. Which basically is what a 150KVA will heat if the load doesn't exceed 112.5.

And last, remind your customer 90 degree (and even 75 or 60) is pretty darn hot.

DaveBowden said:
Have a call to go to tomorrow where the customer says the Leviton single pole slide dimmer in her kitchen is getting hot after the lights haev been on all day. We just installed this a couple of months ago. It is in a 2 gang box with another dimmer. The one getting hot is rated for 600W (500W when installed in a box with 2 dimmers). It has 6 five inch recessed cans with 50W R20 flood lamps in each can for a total of 300W total load.
I don't really want to have to go to a 1000W dimmer if I can avoid it.
Any suggestions as far as things to suspect for the cause?
No the connections aren't loose.
Click to expand...
 
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